aes: Assert precondition required for soundness (#407)

RustCrypto · Feb 13, 2024 · 3e1e83f · 3e1e83f
1 parent 46462cc
commit 3e1e83f
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/aes/src/armv8/expand.rs b/aes/src/armv8/expand.rs
@@ -18,6 +18,9 @@ pub unsafe fn expand_key<const L: usize, const N: usize>(key: &[u8; L]) -> [uint
 
     let mut expanded_keys: [uint8x16_t; N] = mem::zeroed();
 
+    // Sanity check, as this is required in order for the following line to be sound.
+    // We'd rather panic than exhibit undefined behavior.
+    assert!(mem::align_of::<uint8x16_t>() >= mem::align_of::<u32>());
     let columns =
         slice::from_raw_parts_mut(expanded_keys.as_mut_ptr() as *mut u32, N * BLOCK_WORDS);